Currently a good deal of interest has been generated in the analytical community in particle loaded membrane technology and its applications for solid phase extractions as discussed by Hagen et al., "Membrane Approach to Solid Phase Extractions", Analytica Chimica Acta, 236, 157-164, 1990, and by Markell et al., "New Technologies in Solid Phase Extraction", LC/GC, Volume 9, Number 5, 1991. This technology has been shown to be useful for isolation of hydrophobic organic pollutants by adsorptive interactions and has demonstrated the advantages of fast diffusion kinetics when small, high surface area particles are packed closely together in uniform membranes with little or no channeling and with controlled porosity. Van Osch et al. have described a membrane (i.e., a "pellet impervious to a solution of ions) for ion electrodes, Z. Anal. Chem. 271-4, 1975. Solid "membranes" disclosed in U.S. Pat. No. 3,824,169 are imporous (non-porous), chemically inert, composites of gold and salts pressed into pellets which are used in potentiometric electrode technology. Solid "membranes" are distinct from porous particle loaded articles disclosed in U.S. Pat. Nos. 4,153,661, 4,460,642, 4,810,381, 4,906,378, 4,971,736, 5,019,232, 5,071,610, and 5,147,539 for applications in separation science utilizing solid phase extractions.
Particle-loaded, non-woven, fibrous articles wherein the non-woven fibrous web can be compressed, fused, melt-extruded, air-laid, spunbonded, mechanically pressed, or derived from phase :separation processes have been disclosed as useful in separation science. Sheet products of non-woven webs having dispersed therein sorbent particulate have been disclosed to be useful, for example, in respirators, protective garments, fluid-retaining articles, and as wipes for oil and/or water, and as chromatographic and separation articles. Coated inorganic oxide particles have also been enmeshed in such webs.
Contamination of fluids by mercury has been a long-standing environmental concern. Preconcentration or separation of mercury by amalgamation with gold, as a precursor to quantitative analysis of the mercury, has been described. U.S. Pat. No. 3,849,533 discloses powdered carrier material impregnated with a noble metal salt, such as, e.g., silver nitrate, as an absorption medium for mercury. Gold-coated sea sand has been described as a mercury trap in Analytica Chimica Acta 107 pp. 159-167 (1977), as has gold-coated powdered pumice (Japan Kokai 55 084.536, Derwent Abstract). A gold-coated fritted glass disk has been described for mercury collection in Analytical Chemistry 43, pp. 1511-2 (1971). Particulate material is typically described in connection with an extraction column apparatus in which mercury vapor or mercury-containing liquid are passed over the absorbing particulate in a column, after which the absorbing particulate is heated to drive off mercury for direct analysis by, e.g., atomic absorption spectrometry (AAS). In the case of the glass disk, the disk itself was heated to drive off mercury for analysis.
Other references in which gold-coated supports have been used to determine mercury include Analytica Chimica Acta 106, pp 405-410 (1979), Analytica Chimica Acta 220, pp. 257-261 (1989), Chemical Abstracts 111: 83762j (1989), U.S. Pat. Nos. 5,322,628, 5,271,760 and 4,892,567.